This disclosure relates generally to signaling using optical interconnects, and more particularly, but not exclusively, to a fiber-free optical interconnect system for chip-to-chip signaling utilizing free-space optical communications between transmitter and receiver components associated with integrated circuit chips.
State of the art microelectronic systems commonly employ multichip modules. A multichip module includes an array of integrated circuit chips that require signal interconnections between the chips. Multichip modules having only electrical interconnections between chips have only limited performance, and are not suitable for many next-generation computational systems, for example. As such, optical interconnections have been developed with the potential to increase communication speed, and reduce the volume, crosstalk, and power dissipation associated with electrical interconnections.
Numerous methods have been described for utilizing optical beams for interconnection of integrated circuit chips. In one system, optoelectronic transmitters and receivers are coupled to planar optical waveguides. The planar optical waveguides use holographic optical elements (xe2x80x9cHOEsxe2x80x9d) or other coupling gratings to direct optical emissions from the optoelectronic transmitters into the planar optical waveguide. This implementation, while effective, has the disadvantage of being costly, not only in terms of materials and fabrication, but in terms of space occupied by the optical waveguides on a motherboard or other substrate in which the optical waveguides or optical fibers are embedded, for example.
Other methods for utilizing optical beams for interconnection of integrated circuit chips employ HOEs mounted to an optically transparent substrate positioned parallel and adjacent to a circuit board, or other chip carrier, to refract and/or reflect optical signals between chips. One disadvantage of this type of interconnection method is the requirement for the optically transparent substrate, which may contribute to increased complexity of design or packaging requirements in order to facilitate optical communication between chips.